1. Field of the Invention
The present invention relates to a device, method, and storage medium for detecting touch operations on a keyboard of an electronic musical instrument, and the electronic musical instrument.
2. Description of the Related Art
In order to detect the velocity of a key of an electronic musical instrument, it is general to provide two switches (contact nodes) below the key such that the switches are turned on by different press amounts (strokes), and measure a different between the ON times of the switches, and uses the different as velocity information. The measurement starts when a first switch is turned on and finishes when a second switch is turned on. Thereafter, in response to a key press strength obtained from data obtained by the measurement, the tone and volume of a sound source is controlled, whereby a sound generation process is performed (for example, a technology disclosed in JP-A-2013-195647).
Recently, it also has been proposed a related technology capable of performing sound source control which simulated a damper operation of a piano by additionally providing one switch at an intermediate stroke position between two switches (for example, a technology disclosed in JP-A-2005-043553). Here, when the switches are referred to as first, second, and third switch from the shallowest position (the position closest to a key), a structure for detecting key press (touch) strength by the second and third switches is the same as the technology disclosed in JP-A-2013-195647, but it is possible to detect a repetition of key pressing with a small stroke amplitude at the shallow position between the second switch and the third switch, like in an acoustic piano. Also, sound muffling is performed by turning off the first switch while keeping a stroke position according to the related art.
Considering a structure of an acoustic piano, damper-on control (sound muffling control) is performed by the first switch, and a key press velocity and sound generation start timing are controlled by the second and third switches. Therefore, by repeatedly turning on and off the second and third switches while keeping the first switch in an ON state (a damper release state), it is possible to implement overlapping of various tones close to repetitions of key striking on an acoustic piano. This is effective in repeatedly hitting one note or trilling, and is now used.
It is known that, since even though a key is pressed to a lower limit position by a key pressing operation on an acoustic piano, when the key is pressed to a position above the third switch at a constant velocity or higher, a hammer being in contact with an action part of the key gets off the action part, and moves and strikes a string by inertia, it is possible to generate a sound by pressing a key to such a shallow position.
However, according to electronic keyboard instrument technologies of the related art, pressing a key to a position above the third switch is not considered as a key pressing operation. Therefore, there is a problem that a sound might not be generated against player's intention and key press detection performance and performance relating to repetitions of key pressing might be damaged.